Thermo-electric element.



vNo. 781,290.

PATENTED JAN. 31, 1905.

A. L. MARSH. THERMO ELEG Z W w TRIO ELEMENT.

. APPLICATION FILED 00T- 18,1904- UNrrnn Srarns' Patented January 31, 1905.

'lPATlENT Crrron.

ALBERT L. MARSH, OF LAKE BLUFF, ILLINOIS, ASSIGNOR TO WILLIAM A. SPINKS & COMPANY, OF CHICAGO, ILLINOIS, A FIRM.

n-aeninmnrecraic ELEMENT.

- SPECIFICATION forming part of Letters Patent No. 781,290, dated January 31, 1905.

Application filed October 18, 1904. Serial No. 228,944.

To (tZZ whrmt it may concern.-

Be it known that I, ALBERT L. MARSH, a citizen of the United States,residinga't Lake Bluff,

in the county of Lake and State of Illinois, have invented a new and useful Thermo-Electric Element, of which the following is a specification.

My object is to provide an improved thermoelectric element which may be emplbyed with another element to produce a thermo-electric couple having a particularly high meltingpoint.

I have discovered that the metal tungsten, which has a Very high melting-point, may, particularly when alloyed with nickel, be employed as a thermo electric element electronegative to a nickel-copper element. Such a negative element renders it possible to construct thermo -electric couples of comparatively great efficiency which may be subjected at their junctions to intense heat Without danger of injury. By the term negative element in this connection is meant the element of a pair to which the electric current flows from the other or positive element through the junction of the pair when subjected to heat at the said junction.

This invention is the result of experiments carried on with a view to discoveringa readilyavailable metal having a melting-point exceeding, more especially, that of pure copper and which, either alone or when alloyed with other metal or metals, would be either electropositive or electronegative to another highlyrefractory metal or alloy with which it could be joined in a thermo-electric couple and possess the characteristics above set forth as my object, as well as comparatively great strength and durability. I have found that tungsten may when alloyed with nickel be formed into a thermo-electric element strongly electronegative to an element formed of an alloy of nickel and copper. Both the said negative and positive elements have melting-points much higher than that of pure copper and may be subjected without danger to intense heat, thereby establishing adiflerence of electric potential at least equal to any other practical couple of which I am aware withoutthe drawbacks incident to said other couples.

In constructing a thermo-electric battery, for example, I prefer to provide the positive element of each couple of an alloy of nickel (about thi rty-iive per cent.) and copper, (about sixty-five per cent.) This element has a fusing-point above 1,050 centigrade, the appnoximate fusing-point of pure copper. I form the negative element of an alloy of tungsten (about twenty per cent.) and nickel, (about eighty per cent.) Bars of the alloys may be readily welded together at their ends to form thermo-electric couples.

The main advantages of a thermo-electric couple constructed of the elements described lie, first, in the great strength and durability of the couple; second, in the fact that as it may be subjected to heat of great-intensity care in the matter of heat regulation is unnecessary; third, in the fact that the elements may be as thin as desired for rapid heat radiation at the ends farthest from their heated joints, and, fourth, in the fact that the elements may be welded together to produce a joint equally heat-resistant with the body portions of the elements.

In the accompanying drawings I show for purposes of illustration a thermopile of one desirable form in cross-section, with thermoelectric couples connected in series to form an efficient thermo-electric generator.

In the accompanying drawings, Figure 1 is a plan sectional view of a thermopile of one desirable form embodying my improvement, and Fig. 2 a section taken on line 2 in Fig. 1.

A is a combustion-chamber surrounded by a wall B of highly-refractory material, such as fire-clay, asbestos, or the like.

C C indicate thermo-electric couples, each comprising a positive element in the form of a strip a of the nickel-copper alloy mentioned and a negative element in the form of a strip 6 of the tungsten-nickel alloy mentioned. The elements of each couple are preferably electrically welded together to form a joint 0, and they pass through the wall B to extend at their joints in the combustion-chamber A.

The thermo-electric couples are connected in a common manner by means of strips d,which may be of copper, and the thermopile may have the usual terminals, one of which would be positive and the other negative. The couples C may be subjectedin the chamber A, for example, to a direct blast of great intensity from a burner D. The couples will generate an electric current of an efliciency at least equal to that which may be generated by the most eflicient couples hitherto constructed and of which I am aware, and they may be subjected to a heat at their inner endsand a cooling action at their outer ends, which maintains them at approximately the greatest efliciency for an indefinite time without affecting their durability to any material extent. The outer end portions of the couples maybe aircooled or they may be subjected to watercooling or other artificial refrigeration.

I have obtained the best results by employing a tungsten-nickel alloy in substantially the proportions named for the negative element and a nickel-copper alloy in substantially the proportions named for the positive element. My invention, however, is' not' in its broad sense to be limited by this statement, as the main point of my invention lies in the discovery of the use of tungsten-nickel as an element in a thermo-electric couple.

I What I claim as new, and desire to secure by Letters Patent, is

1. Athermo-electric couple, one element of which consists of an alloy of tungsten and nickel.

2. A thermo-electric couple, one element of which consists of an alloy of tungsten and nickel in substantially the proportions set forth.

3. A thermoelectric couple, one element of which consists of an alloy of tungsten and nickel and the other element of an alloy of which nickel forms a part.

4:. A thermo-electric couple, one element of which consists of an alloy of tungsten and nickel and the other element of an alloy of nickel and copper.

ALBERT L. MARSH.

1n presence of W. N. WINBERG, E. P. RICH. 

